Electrical apparatus



Jan. 14, 1930. H. A. THOMPSON ELECTRICAL APPARATUS 5 Sheets-Sheet lINVENTORZ H P:.T/7ornp-5 n,

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Jan. 14, 1930. H. A. THOMPSON 1,743,253

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H. A. THOMPSON ,743,253

ELECTRICAL APPARATUS Original Filed Sept. 14, 1926 Jan. 14, 1930.

5Sheets-Sheet 4 INVENTORZ EH1 AZT/IOFTI OSDn Q'R'W Jan. 14, l 930. H. A.THOMPSON ELECTRICAL APPARATUS 5 Sheets-Sheet 5 Original Filed Sept. 14,1926 Y J QEUN G DDDD MN WMB DJ Q G Q Q fiw fi S E NVENTOR I PatentedJan. 14, 1930 STAS HOWARD A. THOMPSON, 0F EDGEW'OOD BOEQ'UGH,PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF

TION OF PENNSYLVANIA SVJISia'VALE, PENNSYLVANIA, A CORPORA- ELECTRICALAP?ARATUS Continuation of application Serial No. 135,340, filed 1928.Serial My invention relates to electrical apparatus, and is particularlyadapted for, though in no way limited to, railway traffic controllingapparatus.

The present case is a continuation of my co-pending application, SerialNo. 185,340, filed September 14, 1926, for Electrical apparatus, in sofar as the subject matter common to the two applications is concerned.

I will describe two forms of apparatus embodying my invention, and willthen point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1 and 1 are diagrammatic views whichwhen placed end to end in the order named, show one form of apparatusembodying my invention. Figs. 2, 3, d, 5 and 6, are views showing thephase relations and the polarities of the currents in the windings 5 and6 of the relays shown in Figs. 1 and 1. Figs. 7, and 7*, when placed endto end in the order named, form a view showing a modified form of theapparatus illustrated in Figs. 1 and 1 and also embodying my invention.Figs. 8 to 17, inclusive, are views showing the phase relations andpolarities of the current in the windings of the relays shown in Figs.7, 7" and 7 Referring first to Figs. 1 and l the reference characters 30and 30 designate the track rails of a stretch of railway track alongwhich traffic normally moves in the direction indicated by the arrows.These rails are divided by insulated joints 2 into a plurality of tracksections AB, B-C, CD, etc.

Each track section is provided with two relays designated by thereference characters H and K with appropriate exponents, each of whichrelays comprises two windings 5 and 6. The windings 5 of the relays Hand K for each section are connected across the track rails adjacent theentrance end of the section, and the windingsG are constantly. suppliedwith alternating current from the secondary of a transformer designatedby the reference character L with an exponent corresponding to thelocation. The primary of each transformer L is connected with a suitablesource of alternating current which is not shown in the drawings.Interposed between the track September 14, 1926. No. 290,789.

This application filed July 6,

permits current to flow from the rail 30 to this winding but not fromthe winding to the rail 30. Preferably an asymmetric unit 21 isconnected in multiple with the winding 5 of each relay H to shunt outfrom this winding any current which passes through the associated unit19 in the high resistance direction, and preferably an asymmetric unit22 is'connected in multiple with winding 5 of each relay K for a similarreason. It will be seen, therefore, that current of one polarity but notof the other flowing in the track rails of each section will passthrough winding 5 of the relay K for such section, whereas current ofthe second polarity but not of the first will pass through winding 5 ofrelay H for the section.

The two relays for each section control the supply of current to thetrack rails for the section next in the rear from the adjacenttransformer L. The manner in which this control is effected will best beunderstood by tracing the circuits and explaining the operation of theapparatus simultaneously.

As shown in the drawing, the section immediately to the right of point Eis occupied by a train W, so that relays H and K are both tie-energized.Alternating current is then supplied to the primary-27 of the tracktransformer T by a circuit which passes from the secondary oftransformer L through contact ll l4: of relay K contact 10"1O of relay Hprimary 2'? of transformer T contact 99 of relay H and contact 13 f13 ofrelay K t0 the secondary of transformer L of transformer T is of what Iwill term re.- verse relative phase. for transformer T is then fromsecondary 26, through an asymmetric unit 23, track rail 30, asymmetricunit 20, winding 5' of relay K track rail 30 contact 11-11 of relay Kcontact 7-7 of relay H and a reactance 28 to the secondary 26 oftransformer T The, current which is thus supplied to the primary Thesecondary circuit Asymmetric unit 23 is so connected in this circuitthat only what I will term the negative half-wave of the alternatingcurrent from transformer T can flow in the track rails of section D-E.In other words, the positive half-wave of this current is blocked by theunit 23. Since the asymmetric unit 19 associated with relay H preventscurrent of the negative half-wave flowing through winding 5 of thisrelay, it follows that relay H is de-energized. Unit permits current ofthe negative half-wave to flow in winding 5 of relay K however, and sothis relay is energized. Relay K is energized in the reverse directionbecause the relative phase of the current in its winding 5 is reversedwith respect to the phase of the current in its winding 6. Theconditions existing in the windings of relays H and K are illustrated inFigs. 2 and 6. As shown in Fig. 2, full-wave alternating current ofnormal relative phase is supplied to winding 6 of each of these relays,

' whereas as shown in Fig. 6, only the negative half-wave of alternatingcurrent of reverse relative phase is supplied to the track rails, and sorelay K is energized in the reverse direction but relay H isde-energized.

Considering now the supply of current to the rails of section CD,thecircuit for the primary 27 of transformer T is from the secondar r oftransformer L through contact 13"13 of relay K contact 9 9 of relay Hprimary 27 of transformer T contact 1010 'of relay H and contact 14.1 lof relay K to the secondary of transformer L Due to the energizationofrelay K in the 7 reverse direction, the contacts 9, 10, 13 and 14 bythis transformer.

have acted as a pole-changer to reverse the relative phase of thecurrent in the primary 27 of transformer T so that current of normalrelative phase is supplied to section C-D The track circuit for sectionCD is from secondary 26 of trans former T through asymmetric unit 28,upper track rail 30, asymmetric unit 20, winding 5 of relay K lowertrack rail 30, contact 1111 of relay K contact 77 of relay H andreactance 28 to the secondary 26 of transformer T The unit 23 permitsonly the negative half-wave to flow in this circuit, and, consequently,winding 5 of relay K is supplied with the negative half-wave ofalternating current of normal relative phase, so that this relay isenergized in the normal die rection. Relay H is de-energized because theasymmetric unit 19 prevents the negative half-wave of alternatingcurrent from reaching winding 5 of this relay. The conditions in thewindings of relays H and K are indicated in Figs. 2 and 5, from which itwill be apparent that the relay K is energized in the normal direction.7

Considering now track section BC, the primary circuit for transformer Tis from the secondary of transformer L through contact le -14 of relay Kcontact 10 10 of relay K to the secondary of transformer L This currentis of reverse relative phase.

.The secondary circuit for transformer T is from secondary 26, throughreactance 28, asymmetric unit 24, lower/track rail 30*, asymmetriounit19, winding 5 of relayI-I upper track rail 30, contact 88 of relay H andcontact 1212 of relay K to the secondary 26 of transformer T. Theasymmetric unit 24 in this circuit transmits the positive half-wave butnot the negative half wave, and so the asymmetric unit 20 asso ciatedwith relay K prevents this current from reaching winding 5 of thatrelay. I The conditions in the windings of relay H3 are indicated inFigs. 2 and 4, that is, winding. 5 of this relay receives the positivehalf-wave of alternating current of reverse relative 7 tact 1O 1O ofrelay H to the secondary of.

transformer L This current is of normal relative phase. The secondarycircuit for transformer T is from secondary 26, through reactance 28,asymmetric unit 24, lower track rail 30, asymmetric unit 19, winding 5of re lay H upper track rail 30, and contact 88 of relayH to secondary26 of transformer T The symmetric unit 24 transmits the positivehalf-wave but blocks the negative half-wave, and so the current in thiscircuit reaches winding 5 of relay H but not winds ing 5 of relay KInasmuch as winding 50f relay H receives current of normal relativephase, this relay is energized in the normal direction. The conditionsin the windings of the relays H and K are indicated in Figs.

2 and of the drawings, from whichit will be seen that relay K istie-energized because winding 5 The current supplied to the section tothe J left of point A has the same characteristics as that supplied tosection AB. The primary circuit for transformer T is from the secondaryof transformer-L through contact "-9 of relay H primary 27 oftr'ansformer T and contact 10-10 o'f relay H to the secondary oftransformer L Current flows from the secondary 26 of transformer Tthrough reactance 28, asymmetric unit- 24, to the lower track rail 30and from the upper track rail. 30, throughcontact 8-8 of relay H, to thesecondary 26 oftransformer T It will be seen, therefore, that thepositive half-wave of an alternating current of normal relative phase issupplied to the rails of the section to the left of point A.

The relays H and K may be employed to control traffic governing means ofany desired type. As here shown, this trailic governing means is in theform of a wayside signal located at the entrance end of each section anddesignated by the reference character S with an exponent correspondingto the location. Each signal comprises an upper group of lamps 3, and alower group of lamps 4, and each group includes a green lamp Gr, ayellow lamp Y, and a red lamp R.

Referring particularly to signal S inasmuch as both relays H and K arede-ener gized, the two red lamps R are lighted, and all other lamps areextinguished. The circuit for the red lamp R of the upper group 3 isfrom the secondary of transformer L through contact 15 15 of relay Hcontact 17 -17 of relay K lamp R of group 3, to the secondary oftransformer L The circuit for lamp R of group l is from the primary oftransformer L through contact 1515 of relay H contact 1818 of relay Kand lamp R- to the secondary of transformer L Signal S therefore,indicates stop.

Referring now to signal S lamp Y of the upper group 3 is lighted, thecircuit being from the secondary of transformer L through contact 1515of relay H contact 17---1'? of relay K lamp- Y of upper group 3, to thesecondary of transformer L Lamp R of the lower group 4 is lighted, itscircuit being from the secondary of transformer L through contact 1515of relay H contact 1818 of relay K and lamp R of the lower group 4: tothe secondary of transformer L Signal S therefore, indicates proceed,prepared to stop at next signal.

Referring to signal S lamp Y of the upper group is lighted, the circuitbeing from the secondary of transformer L through contact 1515 of relayH contact 17-17 a of relay K and lamp Y of upper group 3 to thesecondary of transformer L Lamp Y of the lower group is also lighted,its circuit being from the secondary of transformer L through contact1515 of relay H contact 1818 of relay K and lamp Y of group 4 to thesecondary of transformer L Signal S therefore, indicates proceed,prepared to stop at second signal in advance.

Considering signal S the lamp Gof the upper group is lighted,the'circuit being from the secondary of transformer L through contact1515 of relay H and lamp G to the secondary of transformer L Lamp Y ofthe lower group is lighted, its circuit being from the secondary oftransformer L through contact 1616 of relay H and lamp Y of group a tothe secondary of transformer L It follows that signal S indicatesproceed, prepared to slow down at next signal.

Considering signal S lamp G of the upper group is lighted, the circuitfor this lamp being from the secondary of transformer L through contact1515* of relay H and lamp G of upper group 3, to the secondary oftransformer L Lamp G of the lower group is also lighted, the circuit forthis lamp being from the secondary of transformer L through contact1616'- of relay H and lamp G of the lower group 4, to the secondary oftransformer L Signal S therefore, indicates proceed.

Referring now to Figs. 7, 7 a and 7 in the form of apparatus here shown,each of the sections A-B, B-C, CD, DE, EF, FM, M-P, and PQ, is providedwith two relays H and K similar to the corresponding relays described inconnection with Figs. 1 and 1 In the present embodiment of my invention,however, winding 5 of each of the relays H and K is connected directlywith the track rails of the associated section.

WVinding 6 of each relay H is supplied with supplied only with halfwaves of one polarity, and the parts are so proportioned that currentflows in one direction through winding 6 of each relay H and in the samedirection but of opposite phase through winding 6 of each relay K. Itfollows that full wave alternating current in the track rails willenergize relays H and K in opposite directions. The currents in windings6 of relays H and K are illustrated in Figs. 8 and 9, re-

spectively.

In addition to the track transformer T, each section is provided with asecond transformer designated by the reference character V with anexponent corresponding to the location and operating at times to supplycurrentto the track rails in parallel with the associated transformer T.

Each section is also provided with a trackway signal S, which in theform here shown comprises nine lampsdesignated by the ref erencecharacters 58 to 66, inclusive, and each arranged to display adistinctive signal indication when energized.

As shown in the drawing, the section immediately to the right of point Qis occupied by a train W. Relays H and K are therefore de-energized andlamp 58 of signal S9 is lighted, the circuit for this lamp passing fromthe right-hand terminal of the second ary of transformer L over contact4545 of relay H contact 5555 of relay K and lamp 58 of signal S back tothe mid-point of the secondary of transformer L Under these conditions,also, a circuit is completed for the primary 27 of transformer T whichmay be traced from the right-hand terminal of the secondary oftransformer L through contact 51-5l of relay K contact 4343 of relay Hand primary 27 of transformer T hack to the mid-point of the secondaryof transformer L The secondary 26 of transformer T is now connected withthe track rails over a circuit which may be traced from the right-handterminal of this secondary, through impedance 28, contact 42-42 of relayH contact 4848 of relay K and asymmetric unit 39 to rail 30 of sectionPQ, and from rail 30 of this section back to the left-hand terminal ofsecondary 26 of transformer T Under the conditions just described,alternating current of normal relative ohase is supplied to the rails ofsection P- but since asymmetric unit 39 is interposed in the secondarycircuit of transformer T only the positive half waves of this cur.- rentflow in the rails of section P-Q,, as shown in Fig. 10. 7

Referring now to the apparatus located at point P, the positive halfwaves of alternating current of normal relative phase supplied to therails of section P.Q energize relay K 55-55 of relay K so that'this lampis in the normal direction, but this current does not energize relay-Hbecause it flows during theinter'vals that winding 6 of relay H isdeenergized, so that the latter relay allows its contacts to assumetheir middle positions. A

5 circuit is therefore completed for lamp 59 of signal S over contact 45of relay H and contact -55 of relay K so that lamp 59 of signal S islighted. A circuit is now closed from the left-hand terminal of thesecondary of transformer L tirough contact 5l+51 of relay K contact43-43 of relay H and primary 27 of transformer T back/co the mid-pointof the secondary of transformer L The secondary 26 of transformer T isnow connected with the railsof section M-P through contact 4242 of relayH contact 48-48 of relay K and asymmetric unit 38. The rails of sectionMP are therefore supplied-with only the .5 negative half waves ofalternating'current of reverse relative phase. This current is showndiagrammatically in Fig. 11. 7

Relay H 'is de-energized, but relay K is energized in the reversedirection by the current flowing in section MP. A circuit is completedfor lamp of signal S over contact 45 l5v of relay H and contact lighted.A primary circuit is now closed for transformer TM, from the left-handterminal of the secondary of transformer L over contact 5151 of relay Kcontact 43-43 of relay H and primary 27 of transformer T hack to themid-point of the secondary of transformer L, The secnmaass ondary 26 oftransformer T is connected with the rails of section FM over a circuitincluding contact 42-42 of relay H contact 4848 of relay K andasymmetric unit 39, so that the rails of section FM are now suppliedwith only the positive half cuit of transformer '1 is now completed fromthe left-hand terminal of'the secondary I of transformer L over contact5252 of relay K contact 4343 of relay H and primary 27 of transformer Tback to the mid point of the secondary of transformer L The secondary26of transformer T is connected with the rails of section E--F overcontact 4242 of relay H and contact 5050 of relay K It will be notedthat neither of the asymmetric units 38 or 39 at point F is included inthe secondary circuit for transformer T so that full wave alternatingcurrent of reverse relative phase is supplied to the rails of sectionEF, as shown in Fig. 13. I

Considering next the apparatus located at point E, the current nowflowing in the railsof section EF energizes relay HE in the normaldirection and energizes relay K in the reverse direction so that acircuit is completed for lamp 62 of signal S over'contact 4545 of relayH and contact 5656 of relay K Furthermore, a primary circuit is closedfor transformer T from the left-hand terminal of the secondary oftransformer L over contact 5252 of relay K contact 43 43 of relay H andprimary 27 of transformer T to the mid-point of the secondary oftransformer L .A circuit is also completed for transformer V whichcircuit may be traced. from the right-hand terminal of the secondary oftransformer L through contact 53 53 of relay K contact V of. alternatingcurrent of reverse relative.

phase are therefore supplied to the rails of section D'E. Furthermore,the secondary 32 of transformer V is connected, through impedance 90,contact 4-141" of relay H contact 47 47' of relay K and asymmetric unit69, with the rails of section DE. The positive half waves of alternating current ofnormal relative phase are therefore supplied to therails of section D-E and the current in this section may be representedby the diagram, Fig. 14.

At point D, relays H and K are both energized in the normal directionand a circuit is completed for lamp 63 of signal S over contact 4545 ofrelay H and contact 5656 of relay K The primary circuit for transformerT may be traced from the right-hand terminal of the secondary oftransformer L through contact 52-52 of relay K contact 4t343 of relay Hand primary 27 of transformer T back to the mid-point of the secondaryof transformer L The secondary of transformer T is now connected withthe rails of section CD through contact 424L2"- of relay H contact 50-50of relay K and asymmetric unit 38. The rails of section C-D aretherefore supplied with the negative half waves of alternating currentof normal relative phase as indicated in Fig. 15. a

The current thus supplied to the rails of section CD energizes relay Hin the reverse direction, but relay K is de-energized, and a circuit iscompleted for lamp 64: of signal S over contact 454[5 of relay H andcontact 57-57 of relay K Current now flows from the right-hand terminalof the secondary of transformer L over contact 43-43 of relay H andprimary 27 of transformer T to the mid-point of the secondary oftransformer L Current is also supplied to transformer V over a c1rcu1twhlch may be traced from the left-hand terminal of thesecondary oftransformer L through contact 5 l5t of relay K contact lt-44 of relay Hand primary 33 of transformer V back to the mid-point of transformer LThe secondary 26 of transformer T is now connected with the rails ofsection BC over contact 4242 of relay H and contact 4949 of relay K andasymmetric unit 38. Furthermore, the secondary 32 of transformer V isnow connected with the rails of section BC over contact lO-4CO of relayH contact 4646 of relay H and asymmetric unit 68. The rails of sectionB-C are therefore supplied with only the negative half waves ofalternating currents of both normal and reverse phases as indicated byFig. 16.

Considering now the apparatus at point B, the current thus supplied tothe rails of section BC energizes both relays H and K in the reversedirection and a circuit is then completed for lamp 65 of signal S overcontact 4:5-4c5 of relay H and contact 57 57 of relay K A primarycircuit is closed for transformer T from the righthand terminal of thesecondary of transformer L through contact 4i3-t3 of relay H and primary27 of transformer T to the mid-point of the secondary of transformer L,The secondary 26 of transformer T is connected with the rails ofsection. A--B over contact 42-42 of relay H and contact 4i9f9 of relay KIt should be observed that neither of the asymmetric units 38 or 39 isincluded in this secondary circuit so that full wave alternating currentof normal relative phase is now supplied to the rails of section A-B asshown in Fig. 17.

Current thus supplied to the rails of section A B energizes relay H inthe reverse direction and energizes relay K in the normal direction. Acircuit is then completed for lamp 66 of signal S over contact 4:545 ofrelay H and contact 57-57 of relay K Primary 2? of transformer T is nowconnected with the right-hand portion of the secondary of transformer Lover contact 43-l3 of relay H The secondary 26 of transformer T isconnected, through contact 42-4t2 of relay H and contact 4;9-4t9 ofrelay K directly with the rails of the section to the left of point A.so that the rails of this section are supplied with full wavealternating current of normal relative phase as shown in Fig. 17.

It will be seen from the foregoing that with the arrangement ofapparatus shown in Figs. 7, 7 and 7 I have provided a system of railwaysignaling in which nine separate and distinct indications are availablewithout the necessity of providing line wires between 10- cations. 7

It should be pointed out that although I I have illustrated relays H andK as three-position two-element relays, the functions of these partscould equally well be performed by twoposition relays of the usualneutral type, the necessary modifications of the circuits being obviousfrom an inspection of the drawing, without further explanation.

Although I have herein shown and described only two forms of apparatusembodyso i ing my invention, it is understood that various 7 changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, two relays each having two windings and each beingselectively responsive to the phase relation of currents in itswindings, means for constantly supplying one winding of each relay withalternating current of fixed relativephase, means for supplying thesecond windings with only the positive or only the negative half wavesof alternating current of one phase or the other, means associated withsaid relays for permittingc'urrent of one polarity but not of the otherto flow in the second winding of one relay and for permitting current ofthe second polarity but not of the first to flow in the second windingof the other relay, and slgnaling means controlled by said relays.

2. In combination, two relays each having two windings and each beingselectively responsive to the phase relations of currents in itswindings, means for constantly supplying one winding of each relay withalternating currentof fixed relative phase, means for supplying thesecond windings with only the positive or only the negative half wavesof alternating current of one phase or the other, an asymetric unit inseries with the second winding of one relay for permitting current ofone polarity but not of the other to fiow through the winding, anasymmetric unit'in series with thesecond winding'ot' the other relay forpermitting current of the second polarity but not of the first to flowthrough the winding, and signaling means controlled by saidrelays. v

- 3. In combination, 7 a relay having two windings and selectivelyresponsive to the phase'relation of currents in said windings, means forconstantly supplying one of said windings with alternating current offixed phase, a circuit for the second winding ineach section having twowindings and each being selectively responsive to the phase relation oicurrents in its windings, means for constantly supplying'one winding ofeach relay with alternating current of fixed relative phase, the secondwinding oI each relay being connected with the rails of the associatedsection, means controlled by the two relays for each section forsupplying the rails of the sec tion in the rear with only the positiveor'only the negative half waves of alternating current of one phase orthe other, means associated with each section for permitting current ofone'polarity but not of the other to flow in the second winding of onerelay for the section and for permitting current of the second polaritybut notof the first flow in the second winding of the otherrelay for thesection, and signalling means for said sections controlled bysaidrelays.

5. In combination, a stretch of" railway track divided into sections,two relays for each section each having two windings and each beingselectively responsive to the phase relation of currents in itswindings, means for constantly supplying one winding of each relay withalternating current of fixed relative phase, the second winding of eachrelay being connected with the rails of the associated section, meanscontrolled by the two relays for each section for supplying the rails ofthe section in the rear with only the positive or only the negative halfwaves of alternating current of one phase or the other, an asymmetricmit interposed between the track rails of each section and the secondwinding of one 6. In combination, two GlGCtIOJ'GSPOHSIVG devices eachhaving two windings and each being selectively responsive to the phasere-' lation of the currents in'its windings, means for constantlysupplying one winding of each device with alternating current of fixedrelative phase, means for supplying the second" windings with only thepositive or only the negative half-waves of alternating current of onephase or the other, and means associated with said devices forpermitting current of one polarity but not of the other to flow in thesecond winding of one device'and for permitting current of the secondpolarity but not of the first to flow in the second winding of the otherdevice. I

7 In combination, two electro-responsive devices each having twowindings and each being selectively responsive tothe phase relation ofthe currents in its windings, means for constantly supplying one windingof each device with alteranting current of fixed relative phase, meansfor supplying the second windings with only the positive or only thenegative half-waves of alternating current of one phase or the other, anasymmetric unit in series with the second winding of one 'de-- vice forpermitting current of one polarity but not of the other to flow throughsuch winding, and an asymmetric unit in series with the second windingof the other device for permitting current of the second polarity butnot of the first to flow through such winding.

8. In combination, a stretch of railway track divided into sections, tworelays for each section each capable of energization in normal andreverse direction, means controlled by the relays of each section forsupplying the rails of the section next in the rear with only thepositive or only the negative haltwaves of alternating current of onephase or the other, and signaling means for said sections controlled bysaid relays.

9. In combination, a stretch of railway track divided into sections, tworelays for each section and responsive selectively to the phase andrelative polarity of current flowing in the track rails of the section,means coniio trolled by the relays for each section for supplying therails of the section in the rear with only the positive or only thenegative half-waves of alternating current of one phase or the other,and signaling means for said sections controlled by said relays.

10. In combination, a stretch of railway track divided into sections,two relays for each section and responsive to the relative phase and thepolarity of current in the track rails of the section, means operatingwhen the two relays for a section are de-energized to supply the railsof the section next in the rear with the positive half-waves of analternating current of normal relative polarity, means operating whenthe first relay for a section is de-energized and the second relay forthe section is energized in reverse direction for supplying the rails ofthe section next in the rear with the positive half-waves of alternatingcurrent of reverse relative polarity, means operating when the firstrelay of a section is de-energized and the second relay for the sectionis energized in normal direction for supplying the rails of the sectionnext in the rear with the negative halt-waves of alternating current ofreverse relative polarity, means operating when the seconc relay of asection is de-energized and the first relay for the section is energizedinnormal direc-' tion for supplying the rails of the section next to therear with the negative half-waves of alternating current of normalrelative polarity, and signaling means for the section controlled bysaid relays.

11. In combination, an electro-responsive device of two windings andselectively responsive to the phase relation of currents in saidwindings, means for constantly supplying one of said windings withalternating current of fixed phase, a circuit for the second windingincluding means for at times supplying only one haltwave of alternatingcurrent of normal or reverse relative polarity and for at other timessupplying the other half-waves of alternating current, means forpermitting the first said half-waves but not the second to flow throughsaid second winding, and other means included in said circuit andresponsive to said second half-waves of alternating current but not tosaid first haltwaves.

12. In combination, a stretch of railway track divided into sections,two relays H and K for each section each having two windings and eachbeing selectively responsive to the phase relation of currents in itswindings, means for constantly supplying one winding of each relay withalternating current of fixed relative phase, means for connecting thesecond winding of each relay with the rails of the associated sectionthrough asymmetric units which permit the positive half-wave but not thenegative half-wave to flow through relay H and which permit the negativehalfwave but not the positive half-wave to flow through relay K, meanscontrolled by the contacts of the relays for each section for supplyingcurrent of normal relative phase to the rails of the section in the rearwhen relay His energized in the reverse direction and relay K isde-energized, and also when the relay H is de-energized and relay K isenergized in the reverse direction, and for supplying current of reverserelative phase to the rails of the section in the rear when both relaysare de-energized and also when relay K is energized in the normaldirection and relay H is de-energized, means for blocking the negativehalf-wave of the alternating current supplied to the rails of a sectionwhen the relay H is energized in the reverse direction and relay K isde-energized as well as when relay H is de-energized and relay K isenergized in the normal direct-ion, and means for blocking the positivehalf-wave of the alternating current supplied to a section when relay His de-energized and relay K is energized in the reverse direction aswell as when both relays H and K are de-energized.

13. In combination, a stretch of railway track divided into sections,two relays for each section each having two' windings and each beingselectively responsive to the phase relation of currents in itswindings, means for constantly supplying one winding of each relay withalternating current of fixed relative phase, means for connecting thesecond winding of each relay with the rails of the associated sectionthrough asymmetric units which permit current of one polarity or theother to fiow through the second winding of one relay and current of thesecond polarity but not of the first to flow through the second windingof the other relay, means controlled by the relays of each section forsupplying alternating current of one relative phase or the other to thetrack rails of the section next in the rear, and means controlled by therelays of each section for blocking either the positive half-wave or thenegative half-wave of the current thus supplied to the rails of thesection next in the rear.

In testimony whereof I atfix my signature.

HOWARD A. THOMPSON.

